The present invention relates to a direct access apparatus and method for a video disc player which can detect a pickup point of a video disc at a high speed.
Conventionally, a rotary disc (to be referred to as a video disc hereinafter) is used as a video signal reproducing medium in a video disc player. The video dics is placed on a turntable and is driven to reproduce video signals therefrom. Spiral recording tracks are formed on the surface of the video disc, and video signals recorded along these tracks are reproduced. A capacitance video disc system and an optical video disc system are both well known as typical video reproduction systems. The video disc rotates together with the turntable and a pickup means traces the signal recording tracks along the video disc, thereby reproducing signals via the pickup means. The pickup means comprises a light source and a photosensor in the optical video disc system, and a stylus electrode which opposes an electrode on the recording tracks in the capacitance video disc system. The stylus is mounted at the distal end of a stylus arm. The stylus arm is fed by an arm mechanism along the video disc to be parallel thereto. In general, the arm mechanism can be moved by an arm feed motor in a radius direction of the video disc. When the arm mechanism is placed above the surface of the video disc, a magnetic means is used to bring the stylus into contact with the recording track of the video disc or to separate it therefrom.
A video disc direct access function is employed in the video disc player of the type described above so as to allow rapid location of a desired position (the startpoint of the recorded signals). When the video disc player has such a direct access function, groove (track) number data recorded on the video disc can be reproduced as a code signal which is then compared with a desired key input signal from a keyboard. When the code signal coincides with the key input signal, a position designated by these signals is determined to be the proper startpoint, thereby starting proper reproduction.
When the direct access function mode is set, the signal corresponding to groove number data and reproduced from the video disc must be monitored during the access operation. In the video disc which has grooves along the recording tracks and which performs signal reproduction by slice sliding contact, the arm feed motor must be rotated at a high speed so as to locate a desired position, while the stylus slidably contacts the surface of the video disc. However, such high-speed operation of the motor causes damage to the video disc or wear and damage to the stylus. If the motor is rotated at a speed so as not to damage the video disc and stylus, however, the time required to find a desired position is prolonged.